JP4973296B2 - Vibration countermeasure support system, vibration countermeasure support method, vibration countermeasure support program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology to quicken and facilitate study of portions and structures to be dealt with. <P>SOLUTION: The system for supporting measures to deal with vibration in accordance with this invention includes a means for setting a plurality of target portions and evaluation points to be dealt with on a model, a means for calculating changes in dynamic characteristics of evaluation points at respective target portions when the rigidity of each target portion is changed, and a means for creating and displaying a graph showing the correlation between the rigidity of a target portion and the dynamic characteristics of an evaluation point according to the result of calculation. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a technology for supporting examination of vibration countermeasures.

  In vehicle development, reducing body vibration is one of the important issues. Therefore, conventionally, methods for performing vibration analysis by computer simulation have been studied.

  For example, Patent Document 1 discloses a method for estimating how a structure vibrates by frequency analysis. In this method, the actual vibration is measured to estimate in what vibration mode the object to be measured vibrates. If the structure is relatively simple, it can be estimated with high accuracy. However, when the object to be measured is a complicated structure such as a vehicle, it is difficult to accurately estimate how vibration is transmitted. Therefore, it was not known what measures should be taken on which part to suppress the vibration.

  Patent Document 2 discloses a method for calculating bending stiffness by detecting bending vibration propagating through a structure and performing frequency analysis. Patent Document 3 obtains a vibration transfer function in a vehicle and based on this. A vehicle body vibration suppressing device that vibrates so as to suppress vibration is disclosed.

Non-Patent Document 1 proposes an optimization method in which initial sensitivity is calculated based on a transfer function synthesis method using a large-scale FEM model, and rigidity is added to a highly sensitive part. . However, in this method, since the optimum calculation is performed from the initial sensitivity by adding the spring, there is a problem that saturation may occur immediately depending on the setting of the optimization calculation, or the deterioration may occur depending on the added amount of the stiffness value. There is also a problem that optimization calculation takes time.
Japanese Patent Laid-Open No. 11-148858 JP 2000-55776 A JP 2000-120768 A Yasuaki Tsurumi and three others, “Optimum Design Method Using a Degenerate Model with a Large-Scale Structure Transfer Function (Development of Vibration Reduction Method Using Additional Stiffness as a Design Variable)”, Transactions of the Japan Society of Mechanical Engineers, Volume C, Vol. 67 663, 2001, 3421-3427.

  To reduce vehicle interior noise and vibration, it is necessary to elucidate the mechanism of its occurrence and incorporate the countermeasure structure into the presumed main factor. However, it is difficult to elucidate the mechanism of occurrence and to identify the main cause because of the complicated phenomenon of booming noise. Moreover, even if the main factor site can be identified, it is extremely difficult to estimate a countermeasure structure (optimum stiffness value) effective for reducing vibration. In the case of an actual vehicle, there are many cases where countermeasures cannot be directly incorporated into the part specified by the simulation (due to structural constraints). Therefore, in the past, the process of selecting countermeasure parts, planning countermeasures and checking effects, and considering contradiction requirements (weight, cost, other performance) must be repeated on a trial and error basis, and it takes about one month to determine the countermeasures. Was.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a technique for quickly and easily examining countermeasure sites and countermeasure structures.

  In order to achieve the above object, the present invention supports examination of measures for reducing vibration by the following means or processing.

  The vibration countermeasure support system according to the present invention includes setting means for setting a plurality of target parts and evaluation points, which are candidate parts to be countermeasured, on the model, and movement of the evaluation points when the rigidity of the target part is changed. Based on the calculation result, a graph showing the correlation between the rigidity of the target part and the dynamic characteristic of the evaluation point is created for each target part. Display means for displaying.

  By comparing the displayed graphs of each region of interest, it is possible to easily determine how much the rigidity of which region is changed and how much the dynamic characteristic (vibration state) of the evaluation point is improved. Therefore, it becomes possible to quickly and easily examine the countermeasure site and the countermeasure structure.

  The model may be a model composed of a large number of nodes, such as a finite element model. At this time, it is preferable that the site of interest is a set of two nodes arbitrarily selected from the plurality of nodes. In a complex structure such as a vehicle body, the number of nodes is enormous, so it is better to narrow the number of nodes selected as a target region to a small number. As a result, the processing time can be shortened and the study can be facilitated.

  It is preferable to further include an analysis unit that calculates a transfer function between the nodes and the evaluation points for each node by performing vibration analysis of the model. The calculating means preferably calculates a change in dynamic characteristics of the evaluation point when the rigidity of the region of interest is changed by a transfer function synthesis method using the transfer function calculated by the analyzing means. By using the transfer function synthesis method, it is possible to easily calculate the dynamic characteristics of the evaluation point with respect to the change in rigidity of the region of interest, so that the calculation time can be shortened.

  The calculation means calculates a change in dynamic characteristics of the evaluation point when the rigidity of the region of interest is changed for a plurality of frequencies, and combines them to obtain a calculation result for a frequency range including the plurality of frequencies. It is preferable to obtain. Since vibration and sound generation have a resonance phenomenon, there is a possibility that the effect cannot be estimated correctly when evaluated at a certain frequency. In this regard, if the configuration is such that the evaluation is performed in a frequency range having a certain band as described above, appropriate examination of vibration countermeasures is facilitated.

  The calculation means preferably calculates not only the change in the dynamic characteristic of the evaluation point when the rigidity is increased, but also the change in the dynamic characteristic of the evaluation point when the rigidity is decreased. The graph may show both calculation results. The correlation between the rigidity of the site of interest and the dynamic characteristics of the evaluation point is not simple, and there is a case where vibration is reduced when the rigidity is reduced. By displaying the graph when the rigidity is increased or decreased in this way, multifaceted evaluation can be performed.

  The display means may arrange the plurality of graphs regularly on the same scale. This facilitates comparison of the graphs of each site of interest.

  The display means may rearrange the plurality of graphs according to a given evaluation index (an index for evaluating the magnitude of the vibration reduction effect) (graph sorting function). This makes it easier to narrow down countermeasure sites. This graph sorting function is particularly useful when the number of graphs is large.

  The present invention can be understood as a vibration countermeasure support system having at least a part of the above means. The present invention can also be understood as a vibration countermeasure support method including at least a part of the above processing, a vibration countermeasure support program for realizing the method, or a computer-readable recording medium on which the program is recorded. . Each of the above means and processes can be combined with each other as much as possible to constitute the present invention.

  For example, a vibration countermeasure support method according to an aspect of the present invention is a method for supporting examination of a countermeasure for reducing vibration, and a plurality of target parts and evaluation points that are candidates for a part to which the computer takes a countermeasure. On the model, processing for calculating the change in the dynamic characteristics of the evaluation point when the stiffness of the site of interest is changed, for each site of interest, and stiffness of the site of interest based on the calculation result A graph showing the correlation between the dynamic characteristics of the evaluation points is created for each region of interest, and processing for displaying those graphs is executed.

  Further, the vibration countermeasure support program as one aspect of the present invention is a program that supports examination of countermeasures for reducing vibration, and includes a plurality of target parts and evaluation points that are candidates for parts to which countermeasures are applied to the computer. On the model, processing for calculating the change in the dynamic characteristics of the evaluation point when the stiffness of the site of interest is changed, for each site of interest, and stiffness of the site of interest based on the calculation result A graph showing the correlation between the dynamic characteristics of the evaluation points is created for each region of interest, and a process of displaying those graphs is executed.

  According to the present invention, examination of countermeasure sites and countermeasure structures can be performed quickly and easily.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings.

  The vibration countermeasure support system according to the embodiment of the present invention is a system for supporting examination (decision of countermeasure part and countermeasure structure) of measures for reducing vibration of a three-dimensional structure such as a vehicle body. Specifically, this vibration countermeasure support system sets candidate sites (target sites) for which countermeasures are to be taken, and calculates changes in evaluation point dynamic characteristics for each target site when the stiffness of the target site is changed. Based on the calculation results, a graph showing the correlation between the rigidity of the target region and the dynamic characteristics of the evaluation point is created for each target region, and these graphs are displayed (this graph is referred to as the “objective function behavior graph”). Called.) The user (measure reviewer) can easily select a countermeasure part and plan a countermeasure structure by comparing the displayed graphs of each target part.

<System configuration>
FIG. 1 is a block diagram showing the configuration of the vibration countermeasure support system. The vibration countermeasure support system 1 includes functions such as a condition setting unit 10, a target region setting unit 11, a vibration analysis unit 12, a countermeasure effect calculation unit 13, and a graph display unit 14. The condition setting unit 10 is a function for inputting conditions necessary for the processing of the vibration countermeasure support system, and the target region setting unit 11 is a function for setting the target region on the model. In the present embodiment, the condition setting unit 10 and the target region setting unit 11 correspond to the setting unit of the present invention. The vibration analysis unit 12 corresponds to the analysis unit, the countermeasure effect calculation unit 13 corresponds to the calculation unit, and the graph display unit 14 corresponds to the display unit.

  The vibration countermeasure support system 1 is typically a general-purpose device including an arithmetic processing unit (CPU), a main storage device (memory), an auxiliary storage device (such as a hard disk), a display device, and an input device (such as a mouse and a keyboard). It can be configured from a computer and a program operating on the computer. The functional elements shown in FIG. 1 are realized by an arithmetic processing unit executing a program and controlling hardware resources such as a main storage device, an auxiliary storage device, a display device, and an input device as necessary. However, a part of these functional elements may be replaced with a dedicated chip. Further, not all of these functional elements need to be executed by a single computer, and a plurality of computers may cooperate to constitute a vibration countermeasure support system.

<Process flow>
FIG. 2 is a flowchart showing the flow of processing of the vibration countermeasure support system 1. The function and operation of the vibration countermeasure support system 1 will be specifically described with reference to this flowchart.

In the present embodiment, an automobile body is taken as an example of a three-dimensional structure to be analyzed (of course, the present invention can be applied to other three-dimensional structures). And, using the Finite Element Method (FEM) as a vibration analysis method, FEM as model data
Use the model. In the FEM model, a three-dimensional structure is composed of a plurality of elements (shell elements, beam elements, etc.). Each element has a plurality of nodes, and the elements are connected by nodes. In a complex three-dimensional structure such as an automobile, a model is composed of many elements on the order of over one million.

  As shown in FIG. 2, first, in step S <b> 1, the user inputs various conditions using the condition setting unit 10. The conditions input here are an excitation point, an evaluation point, a frequency, and the like.

  The “excitation point” is a point to which an external force (vibration) is applied, and the “evaluation point” is a point (a point of interest) that is an evaluation target of the vibration (pronunciation) level. As illustrated in FIG. 3, typically, a vibration source such as an engine mount is set as an excitation point, and a part arranged near the driver's ear such as a roof panel is set as an evaluation point. The The excitation point and the evaluation point may be selected from the nodes on the model, or may be set at a position other than the node (for example, the center of the element). Each point has multiple degrees of freedom, but in order to simplify the problem, the direction of external force applied to the excitation point (excitation direction) and the direction of vibration evaluated at the evaluation point (evaluation direction) are one degree of freedom. It may be narrowed down to.

  “Frequency” is a frequency (frequency of interest) to be evaluated for vibration level. For example, when the result shown in FIG. 4 is obtained by a vibration simulation performed in advance (the horizontal axis is the vibration frequency (Hz) of the evaluation point, and the vertical axis is the sound pressure level of the evaluation point). It can be seen that attention should be paid to the frequency around 180 Hz to 190 Hz.

  In the condition setting unit 10 of this embodiment, for example, it is possible to set a single frequency such as “185 Hz”, but it is also possible to set a frequency range (frequency band) of an arbitrary width. . For example, if the minimum frequency “180 Hz”, the step value “5 Hz”, and the number of frequencies “4” are input, four frequencies of 180 Hz, 185 Hz, 190 Hz, and 195 Hz are set. Any frequency range input method may be used. For example, a minimum frequency, a maximum frequency, and the number of frequencies (or step values) may be input, or a plurality of frequency ranges such as “180 Hz, 185 Hz, 190 Hz, 195 Hz” may be input. You may enter the value of. Alternatively, the user can input only one frequency (for example, 185 Hz), and the condition setting unit 10 can automatically set the frequency range (for example, select a range of ± 10 Hz around 185 Hz as the frequency of interest). is there.

  When a frequency range (or a plurality of frequencies) is set here, the subsequent analysis processing is executed for each target frequency. Then, the total result of the analysis at each frequency is evaluated as the final result. For example, if the acceleration amplitude at the evaluation point is evaluated, the acceleration amplitude when vibration is applied at each frequency may be calculated, and a statistical value or a representative value obtained from them may be evaluated as a final acceleration amplitude value. As the statistical value, for example, a total value, an average value, a variance value, and the like can be considered, and as the representative value, for example, a maximum value, an intermediate value, a minimum value, and the like can be considered. The reason why the evaluation is performed not only at one frequency but also at a plurality of frequencies (frequency range) is as follows. That is, since vibration and sound generation have a resonance phenomenon, there is a possibility that the effect cannot be estimated correctly when evaluated at a certain frequency. For example, even if the vibration at 185 Hz can be reduced, it is meaningless if the vibration at 190 Hz is increased. On the other hand, if the configuration is such that the evaluation is performed in a frequency range having a certain band as described above, the optimum solution as a whole can be searched, and appropriate examination of vibration countermeasures can be facilitated.

  Next, in step S <b> 2, the site of interest setting is performed by the site of interest setting unit 11. Specifically, as shown in FIG. 5, an arbitrary number of nodes are first selected from a large number of nodes constituting the FEM model. The nodes selected here are referred to as “focused nodes”, and a model composed of the focused nodes is referred to as a “reduced model”. The user may select the focused node, or the focused region setting unit 11 may automatically select the focused node. A set of two target nodes adjacent on the contracted model is a “target part”. In complex three-dimensional structures such as car bodies, the number of nodes is on the order of one million, so it is unrealistic to examine countermeasures for each node. Therefore, in this embodiment, a contracted model with narrowed nodes is used. As a result, processing time can be shortened and countermeasures can be easily studied.

  The reduced model can be confirmed on the screen. At this time, the entire model (vehicle) is displayed by displaying not only the focused node but also a line segment connecting adjacent focused nodes as shown in FIG. 5 (this line segment corresponds to the focused region). The shape can be imaged.

  In step S3, the vibration analysis unit 12 performs vibration analysis (finite element method analysis) of the FEM model based on the conditions set in step S1. As a result of the vibration analysis, information such as displacement, acceleration, nodal force, stiffness, and mass of each node (each element) regarding each frequency of interest is obtained.

  In step S4, the vibration analysis unit 12 calculates a transfer function between the nodes and the evaluation points based on the result of the vibration analysis for each node, and creates a transfer function matrix that summarizes the transfer functions. This transfer function matrix is output to a file and used for the process of step S6.

  The transfer function corresponds to the response of the evaluation point when a unit load is applied to the node. However, it is not realistic to perform vibration analysis for each node. Therefore, in this embodiment, attention is paid to the reciprocity of the transfer function. In short, reciprocity means that “the response of point B when a unit load is applied to point A” and “the response of point A when a unit load is applied to point B” are equivalent. It is a property. Using this property, in the vibration analysis in step S3, the evaluation point is subjected to unit excitation, and the displacement of each node at that time is obtained. As a result, it is possible to obtain transfer functions for all degrees of freedom of all nodes in one vibration analysis calculation. If there are a plurality of frequencies of interest, the evaluation point may be unit-excited at each frequency of interest and a transfer function for each frequency of interest may be calculated.

  In step S5, the countermeasure effect calculation unit 13 causes the user to set parameters necessary for calculating the countermeasure effect. Here, the measure for reducing the vibration is specifically to change the rigidity of the region of interest (between two nodes of interest). The change in the rigidity of the site of interest can be imaged as the addition of a spring to the site of interest. By changing the rigidity of the spring to be added, the amount of change in the rigidity of the region of interest can be arbitrarily adjusted. If a plus stiffness spring is added, the stiffness of the region of interest increases. In addition, the rigidity of the region of interest can be reduced by thinking of a negatively rigid spring. This is because the correlation between the rigidity of the site of interest and the dynamic characteristics of the evaluation point is not simple, and there is a case where vibration is reduced when the rigidity is reduced. As a parameter input in step S5, a range of rigidity of the spring added to the target region (that is, a change margin of rigidity of the target region) is set.

In step S6, the countermeasure effect calculation unit 13 determines the region of interest based on the information such as the excitation point set in step S1, the transfer function matrix generated in step S4, and the parameter input in step S5. The change of the dynamic characteristic (acceleration amplitude) of the evaluation point when the rigidity of the object is changed is calculated for each target region. Specifically, the countermeasure effect calculation unit 13 first divides the range of the spring stiffness input in step S5 by a predetermined number of steps (for example, if the number of steps is 20, 20 additional spring stiffness values are added). The value of is obtained.) Then, the countermeasure effect calculation unit 13 calculates the acceleration amplitude of the evaluation point when the spring rigidity is added to a certain target site by the transfer function synthesis method. If there are 100 sites of interest, 20 spring stiffness additions, and 5 frequencies of interest, the acceleration amplitude of the evaluation point is calculated for 100 × 20 × 5 = 10000 cases. If vibration analysis (finite element method analysis) is performed for all cases, it will take an enormous amount of time. Compared to this, by using the reduced model and transfer function synthesis method as in this embodiment, Time reduction. The calculation result of the countermeasure effect calculation unit 13 is output in a file format such as CSV.

  In step S7, the graph display unit 14 reads the calculation result file of the countermeasure effect calculation unit 13, and creates a graph (objective function behavior graph) indicating the correlation between the rigidity of the target region and the dynamic characteristics of the evaluation point for each target region. And display these graphs on the screen. Such a function of the graph display unit 14 can be realized by a spreadsheet software macro, for example.

  FIG. 6 shows a display example of the objective function behavior graph. One graph corresponds to one site of interest. The horizontal axis of the graph indicates the amount of added spring stiffness, and the vertical axis indicates the degree of change in the acceleration amplitude at the evaluation point (= acceleration amplitude after spring addition / acceleration amplitude before spring addition). Note that the degree of change in the acceleration amplitude of the evaluation point may be displayed as a decibel (dB) value.

  The graph display unit 14 displays the objective function behavior graphs regularly arranged on the same scale. This facilitates graph comparison. The graph display unit 14 has a graph sorting function for rearranging the objective function behavior graph according to various evaluation indexes. As the evaluation index, various indices such as acceleration amplitude, degree of change in acceleration amplitude (reduction allowance), sum of acceleration, and sum of squares of acceleration can be adopted. For example, if the graph is sorted in descending order of the degree of change (reduction allowance), the region of interest with a large vibration reduction effect is displayed at the top.

  Using the system described above, by comparing the displayed objective function behavior graphs of each target region, how much the stiffness of which region is changed and how much the evaluation point dynamics (vibration) is You can easily judge whether to improve. Therefore, it becomes possible to quickly and easily examine the countermeasure site and the countermeasure structure.

  In addition to the change in the dynamic characteristics of the evaluation point when the stiffness is increased, the change in the dynamic characteristics of the evaluation point when the stiffness is reduced is also calculated. Therefore, multi-faceted evaluation is possible.

  The above embodiment is merely an example of the present invention. The scope of the present invention is not limited to the above embodiment, and various modifications can be made within the scope of the technical idea.

FIG. 1 is a block diagram showing the configuration of the vibration countermeasure support system. FIG. 2 is a flowchart showing the flow of processing of the vibration countermeasure support system. FIG. 3 is a diagram illustrating an example of an excitation point and an evaluation point. FIG. 4 is a graph showing the frequency of interest. FIG. 5 is a diagram illustrating an example of the frequency of interest. FIG. 6 is a diagram illustrating a display example of the objective function behavior graph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vibration countermeasure support system 10 Condition setting part 11 Focus part setting part 12 Vibration analysis part 13 Countermeasure effect calculation part 14 Graph display part

Claims (9)

A system that supports the study of measures to reduce vibration,
A setting means for setting on the model a plurality of target parts and evaluation points that are candidate parts for which to take countermeasures;
A calculation means for calculating a change in dynamic characteristics of the evaluation point for each target region when the rigidity of the target region is changed;
Based on the calculation results, a graph showing a correlation between the rigidity of the site of interest and the dynamic characteristics of the evaluation point is created for each site of interest, and display means for displaying those graphs;
A vibration countermeasure support system characterized by comprising: The model is a model composed of a large number of nodes,
The vibration countermeasure support system according to claim 1, wherein the site of interest is a set of two nodes arbitrarily selected from the plurality of nodes. Analyzing means for calculating the transfer function between the nodes and the evaluation points for each node by performing vibration analysis of the model,
The calculation means calculates a change in dynamic characteristics of an evaluation point when the rigidity of a region of interest is changed by a transfer function synthesis method using the transfer function calculated by the analysis means. Item 3. The vibration countermeasure support system according to item 2. The calculation means calculates a change in dynamic characteristics of the evaluation point when the rigidity of the region of interest is changed for a plurality of frequencies, and combines them to obtain a calculation result for a frequency range including the plurality of frequencies. The vibration countermeasure support system according to claim 1, wherein the vibration countermeasure support system is obtained. The calculation means calculates not only the change in the dynamic characteristic of the evaluation point when the rigidity is increased, but also the change in the dynamic characteristic of the evaluation point when the rigidity is decreased,
The vibration countermeasure support system according to any one of claims 1 to 4, wherein both calculation results are shown in the graph. 6. The vibration countermeasure support system according to claim 1, wherein the display unit regularly arranges the plurality of graphs on the same scale. The vibration countermeasure support system according to claim 1, wherein the display unit rearranges the plurality of graphs according to a given evaluation index. A method for supporting the study of measures to reduce vibration,
Computer
A process of setting a plurality of target parts and evaluation points, which are candidate parts for the countermeasure, on the model;
A process for calculating a change in the dynamic characteristics of the evaluation point when the rigidity of the target region is changed for each target region;
Based on the calculation results, a graph showing the correlation between the rigidity of the site of interest and the dynamic characteristics of the evaluation point is created for each site of interest, and processing for displaying those graphs;
The vibration countermeasure support method characterized by performing this. A program that supports the study of measures to reduce vibration,
On the computer,
A process of setting a plurality of target parts and evaluation points, which are candidate parts for the countermeasure, on the model;
A process for calculating a change in the dynamic characteristics of the evaluation point when the rigidity of the target region is changed for each target region;
Based on the calculation results, a graph showing the correlation between the rigidity of the site of interest and the dynamic characteristics of the evaluation point is created for each site of interest, and processing for displaying those graphs;
A vibration countermeasure support program characterized by causing

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